mkvmerge: chapter generation: if the name template given by--generate-chapters-name-template is empty, no names (ChapterDisplay
master elements with ChapterString/ChapterLanguage children) will be
generated for the chapter atoms.

mkvmerge: chapters: chapter names generated from MPLS files will now use the
name template if one is set via --generate-chapters-name-template.

mkvmerge: mkvmerge will no longer abort with an error message if no audio,
video and subtitle tracks should be multiplexed. This allows copying of
chapters from non-chapter source files (e.g. Matroska or MP4 files).

MKVToolNix GUI: the font size in the tool selector on the left will scale
with the font size the user selects in the preferences.

MKVToolNix GUI: the GUI will no longer automatically resize the columns in
tree and list views to match the content size. Instead it remembers and
restores the widths set by the user.

MKVToolNix GUI: multiplexer: the chapter name template will now be set
automatically to the name template in the preferences’ “chapter editor”
section. Additionally the option --generate-chapters-name-template … will
be passed to mkvmerge in situations when mkvmerge will generate chapters
(either because automatic generation is enabled or if chapters are generated
for MPLS playlists).

MKVToolNix GUI: chapter editor: if the chapter name template is empty,
chapters will be generated without names.

Free and open-source Matroska software MKVToolNix v21.0.0 was released days ago. The biggest change is that mkvinfo’s GUI portion has been removed.

New features and enhancements in MKVToolNix 21.0.0:

mkvmerge: track statistics tags: the TagDefault element will not be written anymore as it was always set to the default value 1 anyway.

mkvmerge, MKVToolNix GUI: JSON files can now contain C++-style line comments outside of strings (e.g. something like this: // this is ignored). Such comments, even though not part of the official JSON specifications, are now ignored when reading JSON files.

MKVToolNix GUI: chapter editor: opening a Matroska file without chapters in it will now open the file in an empty chapter editor instead of showing an error message.

MKVToolNix GUI: an “info” tool has been added, replacing the functionality of mkvinfo’s GUI. The functionality is not on par yet but will be for release v22.

mkvinfo: most of its code was re-written in order to lay the groundwork for including its functionality in MKVToolNix GUI but with more features than the existing mkvinfo GUI. Changes include but aren’t limited to:

Several element names are a bit clearer (e.g. Maximum cache instead of MaxCache).

All timestamps and durations are now output as nanoseconds in formatted form (e.g. 01:23:45.67890123). All additional formats (e.g. floating point numbers output in seconds or milliseconds) were removed.

Element names for chapters and tags are now translated if a translation is available.

Elements located in wrong positions within the Matroska document are handled better.